1. Field of the Invention
The present general inventive concept relates to an apparatus to decode audio data constructed with a plurality of layers such as bit-sliced arithmetic coding (BSAC), and more particularly, to a method and apparatus to conceal an error in a decoded bitstream.
2. Description of the Related Art
In the process of transmitting an encoded audio signal through a wired/wireless network such as a terrestrial-digital multimedia broadcasting (T-DMB) or an Internet protocol (IP) network, errors occur. In this case, if the errors are not properly treated, decoding cannot be correctly performed due to a transmission error, and sound quality significantly deteriorates.
Conventionally, in order to conceal the errors of an audio signal, a muting method of reducing an influence of the errors on an output by reducing a sound volume of a frame having the errors, a repetition method of copying data of a previous frame to a frame having errors, and a method of restoring a time domain sample of a frame having errors by using a previous frame by performing interpolation or extrapolation, are used.
However, in general, in order to conceal errors existing in the audio signal, the whole data corresponding to a unit frame including errors is restored by using another frame instead of restoring only a part where errors occur. Therefore, there is a problem in terms of deterioration in output sound quality.